Description
Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Multipart::Parser#handle_mime_head parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated String#index searches combined with String#slice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticated attacker can send a crafted multipart/form-data request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing. This results in a denial of service condition in Rack applications that accept multipart form data. This issue has been patched in versions 3.1.21 and 3.2.6.
Problem types
CWE-407: Inefficient Algorithmic Complexity
CWE-400: Uncontrolled Resource Consumption
CWE-770: Allocation of Resources Without Limits or Throttling
Product status
>= 3.2.0, < 3.2.6
References
github.com/rack/rack/security/advisories/GHSA-v6x5-cg8r-vv6x